﻿Shader "UnityShadersBook/Chapter08/Chapter08-AlphaBlend"
{
    Properties
    {
        _Color( "Main Tint", Color ) = ( 1,1,1,1 )
        _MainTex( "Main Tex", 2D  ) = "white" {}
        _AlphaScale( "Alpha Scale", Range( 0,1 ) ) = 1
    }
    SubShader
    {
        Tags { "Queue" = "Transparent" "IgnoreProjector"= "True"  "RenderType" = "Transparent"  }

        Pass
        {
            Tags { "LightMode" = "ForwardBase" }

            ZWrite Off
            //BlendOp Max
            //Blend One One
            Blend SrcAlpha  OneMinusSrcAlpha

           

            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"
            #include "Lighting.cginc"

            fixed4 _Color;
            sampler2D _MainTex;
            fixed4 _MainTex_ST;
            fixed _AlphaScale;

            struct a2v
            {
                float4 vertex : POSITION;
                float3 normal : NORMAL;
                float4 texcoord : TEXCOORD0;
            };

            struct v2f
            {
                float4 pos: SV_POSITION;
                float3 worldNormal : TEXCOORD0;
                float3 worldPos: TEXCOORD1;
                float2 uv : TEXCOORD2;
            };

            v2f vert( a2v v )
            {
                v2f o;
                o.pos = UnityObjectToClipPos( v.vertex );
                o.worldNormal = UnityObjectToWorldNormal( v.normal );
                o.worldPos = mul( unity_ObjectToWorld, v.vertex ).xyz;
                o.uv = TRANSFORM_TEX( v.texcoord, _MainTex );
                return o;
            }
            
            fixed4 frag( v2f i ):SV_TARGET
            {
                fixed3 worldNormal = normalize(i.worldNormal );
                fixed3 worldLightDir = normalize( UnityWorldSpaceLightDir( i.worldPos ) );

                fixed4 texColor = tex2D( _MainTex , i.uv );
                fixed3 albedo = texColor.rgb * _Color.rgb;
                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;

                fixed3 diffuse =  _LightColor0.rgb * albedo * saturate( dot( worldNormal, worldLightDir ) );


                return fixed4( ambient+diffuse, texColor.a * _AlphaScale );
            }

            ENDCG
        }
    }
    Fallback "Transparent/Cutout/VertexLit"
}
